That's fair, you're being charged to stick with a higher cost (but slightly more reliable) carrier in that case. I use a Verizon network, but third party, and pay $10 a month for 1 gig of data. They do not do replacement phones, only signup phones, but I'm guessing I pay about $50 less per month than you would for my 1 gig. That works out to $1200 difference for 2 years.

Edit: My plan also requires you have Comcast internet. So, that has to also be taken into consideration, but Comcast is the only good option where I live.